Approach lock release in railway signaling systems



Dec., 5 1950 F. CADMAN 2,53232 APPROACH LOCK RELEASE IN RAILWAY SIGNALING SYSTEMS Filed Feb. 6, 1946 2 Sheets-Sheet l r l L m w am S mm@ www SND m m S 4Aval? C'aman Clif,

2MB BIL!" v 2 Sheets-Sheet 2 n INVENTOR [120E Cadmqn Haz/jm HIS ATTORNEY F. CADMAN APPRUACH LOCK RELEASE IN RAILWAY SIGNALING SYSTEMS Filed Feb. 6, 1946 signals 4LA and 2LA, while westbound traffic over switch 3 is governed by signal ISLB and westbound traic over switch I is governed by signal 2LB. These signals, as indicated in the diagram, are of the semaphore type and may be similar for example to the signal shown in Letters Patent of the United States No. 611,943, granted to J. G. Schreuder on October 4, 1898. Each signal is provided with an arm or semaphore blade having a or stop position, a 45 or caution position, and a 90 or clear position, and each signal has a suitable operating mechanism for operating the associated blade to the positions mentioned.

The signals 4RA and 4LA govern traino in l.

opposite directions in section 3T and hence these signals may be considered as opposing signals. Signal 2BA governs trailic on track M approaching signal dRA and may therefore be considered an approach signal for signal 4RA. Each of the signals illustrated in the drawing is controlled through the medium of home and distant relays in a manner corresponding to that illustrated in the drawing for the control of signal ILA. When the associated home relay ALAH is released, signal 4LA is deenergized and occupies its stop or 0 position; when relay 4LAH is picked up to close the front point of its contact a, signal 4LA is energized over an obvious circuit including the front point of that contact and is caused to operate to its caution or position; and when relay LAH is picked up and distant relay 4LHD is operated to its reverse position, another ele ment of signal 4LA becomes energized over the front contact of relay LAH and contact a of relay 4LHD closed in its reverse position, whereupon signal 4LA is caused to operate to its clear or 90 position.

Each of the signals is provided with circuit controlling contacts operated by the associated mechanism to occupy different positions according to the position of the semaphore blade. For example, signal 2LA illustrated in Fig. la is provided with contacts a and b operated by the mechanism of signal 2LA so that when the signal is in its stop position, its contacts a and b are in the positions illustrated in the drawing and remain in these positions until signal ZLA operates to its caution or 45 position. At or between its 45 and 90 (clear) positions contacts a and b are operated to the reverse positions indicated by dotted lines in the drawing. The signals are also provided with 0 position indication relays which correspond to relay 4RP provided for signals IRA and RB. Relay `4RP is energized over an obvious circuit passing from one terminal B of a suitable source of current such as a battery not shown but having its opposite terminals designated by the reference characters B and C, through contact a. of signal 2RA closed in the 0-45" position of that signal, contact a of signal 4RB closed in its 0 position, contact a of signal 4RA closed in its 0 position and the winding of relay 4BP to terminal C. The control of the relay 4RP is such that the relay is deenergized whenever signal RA or 4RB operates from its 0 (stop) position, or whenever signal ZRA operates beyond its 45 (caution) position to its 90 (clear) position. Relay 4LP is similarly controlled by signals 4LA, 4LB. and the signal (not shown) in approach to signal GLA. 1 It is contemplated that the signals and switches shown in the drawing are controlled from a remote oice through the medium ofa communication system of the centralized trailic control 4 l type. The system may for example be of the type shown in Letters Patent of the United States No. 2,229,249, granted to Lloyd V. Lewis on January 2l, 1941, Ibut modied to correspond with the showing of Letters Patent of the United States No. 2,197,130, grantedA to Lloyd V. Lewis on April 16, 1940, this modification providing for arrangements to enable the switch control relay 3WS and signal control relays lRHS and ILHS to be of the stick polar type, as shown in Fig. 1b, all of these relays being of the stay-where-put type arranged to be held in their last operated positions when deenergized. Each of the switch and signal control relays has a normal position in which its polar armature is operated to its left-hand position, as viewed in the drawing, and a reverse position in which its polar armature is operated to its right-hand position.

The switch control relay SWS controls a power-operated switch mechanism (not shown) for effecting operation of switch 3 oy power in response to control from the remote oice, and also cooperates with the switch indicating relays 3NW and SRW to control switch correspondence :j relays 3NWC and 3RWC in such a manner that relay 3NWC is energized over an obvious circuit including the front point of contact a ofvrelay 3NW and contact a of relay SWS in its normal position, while relay 3RWC will be energized when contact a of relay 3RW is closed in its front position and contact a of relay 3WS is operated to its reverse position.

Relay GRHS cooperates with distant relay dLHD of signal 4LA to control an approach relay 4RAR over a circuit including contact aof relay 4RHS closed in its normal position, contact b of relay ALHD closed in its front position and the winding of relay ARAB. to terminal C. When relay dRAR picks up, its contact a is operated to its front position to close an alternate path in the circuit for this relay around contact b of relay ALHD, and this alternate stick circuit path holds relay QRAR energized in the event that relay IILHD releases while contact a of relay 4RHS is retained in its normal position.

The reference character dLAR designates another approach relay controlled over a circuit indicated conventionally in the drawing as including a contact x which represents the inclusion of front contacts of all track relays of the track sections between signal 4LA and its approach signal (not shown).

The reference character 4AS designates a control relay for controlling a time element relay TE over an obvious circuit including the front point of contact a of relay 4AS. Relay 4AS is energized over a circuit including contact a of relay 3TR closed in its front position and then passing through one or another of two alternate paths, one path including contact a of approach locking relay #IRAS closed in its back position, front contact a of relay 4RP and contact b of relay RHS closed in its normal position; and the other path extending through contact a of approach locking relay 4LAS closed in its back position, front contacta of relay 4LP and contact a of relay 4LHS closed in its normal position.

The approach locking relay iRAS is provided with an energizing circuit extending from terminal B through contact b of relay 4RHS closed in its normal position, contact a of relay lIRP closed in its front position, contact b of relay 4RAR closed in its front position, contact a of relay 3NWC closed in its front position and the Winding of relay 4RAS to terminal C. As is VVThe distant control relay ZRHD of signal ERA'is controlled lby a circuit which is correspondingly similar to the circuit for relay ilLHD as will be apparent from an inspection of the drawing. v

Relay ERD is a slow releasing repeater of relay ZRHD in its operated i. e. right-hand-position and is controlled over a circuit passing from terminal B through contact b o relay ZRHD closed in its iront position, contact c of relay ERI-ID closed in its reverse position and the winding of relay 2RD to terminal C. When contact c of relay ZRHD is operated to its normal position, relay RD is provided with a short circuit path connected across its terminals and through which current circulates during the decay of flux in relay ERD to snub the release of that relay. Relay iLD is a repeater of relay LHD in its oper-ated position and is controlled by relay iLI-lD in a manner corresponding to the control of relay 2R13V by relay ZRHD as will be obvious from an inspection of the drawing.

Relay QRAS which has a contact interposed in a circuit path traced for relay LI-ID, is controlled by relay 2RHS through circuits (not shown) similar to the circuits traced for the control of relay @LAS by relay @LHS but involving apparatus provided at the other end of passing track P. Relay lRWC is controlled by switch l and Vits related control apparatus in a manner corresponding to the control of relay SRWC by the circuits traced for the latter relay.

I shall now describe the manner of operation or the apparatus embodying my invention. In the description l shall assume that the stretches of track M and l?, within the limits of the sections represented in the drawing, are vac-ant; that track switches l and 3 occupy their normal positions; and that all of the signals represented in the drawing are in their stop or positions. In this condition o the apparatus as represented in the drawing, all track relays are picked up; remotely controlled switch opn erating relay SWS and signal operating relays @Rl-ES and 'lLHS are in their normal or left-- hand positions; normal position indicating relay BNW and switch correspondence relay BNWC arepicked up; approach relays RAR and LAR are picked up; signal repeating relays ARP and llLP are energized; approach locking relays ARAS, lLAS and ERAS are picked up; distant control relays llLHD and ERI-iD are energized in their normal directions so that their contacts occupy their Vleft-hand positions respectively; relay @Rl-ll) energized; and al1 other relays representedlin the drawing are released. I shall now assume that the operator clears Ysignal RA by manipulation of the controlling lever of the communication system in the central oiiice to cause relay @RHS to operate its contacts to their reverse or right-hand positions. When this happens, contact d of relay BRI-IS closes in its reverse position to energize relay 4BP over its previously traced circuit; relays and BRAS become deenergised; and relay @RAI-I becomes energized over its previously traced circuit including contact b of relay lRl-IS closed in its reverse position, front contact b of relay 4BP, front contact b of relay LAS and back contact l? of relayvfRAS. The energization of relay ARAl-I results in the closing of its contact a to its front position so that signal RA operates to its cauktion position. It is understood, ofcourse, that distant relay 4RHD provided for signal ARA controls the operation of that signal to its clear positionA under certain conditions, but the control of the signal by this relay and the control` of the distant relay itself are not shown in order to avoid unnecessary complication of the draw- The operation of signal lRA to its caution position results in the opening of contact a of signal @RA to deenergize relay liRP, and in the operation of contacts b and c of signal liRA to their reverse positions to reverse the polarity of energization of relay QRHD which thereupon operates its polar armature to its right-hand position. Relay ERD now becomes energized, and the contact of relay QRl-lD in its reverse position conditions signal ERA to operate to its clear position should signal ZRA be controlled from its stop position by the operator from the C. T. C. oflice through the medium of relay ZRHS represented in the drawing.

If the operator clears signal 2BA through the medium of the actuation of the proper signal controlling lever at the C. T. C. oiiice, relay ZRAl-I will be picked up through circuits and related apparatus which correspond to the circuits shown in Fig. lb for relay GRAH, and with relay KRED reversed, signal ERA will be operated to its clear position. Contact a of signal ZRA in the circuit of relay iRP is now opened, and contact a of relay ERAS in the circuit of relay ALI-ID also is opened because relay ZRAS becomes deenergized in the control or relay ilRAI-I in a manner corresponding to the release of relay RAS in the control .of relay 4RAH. Relay 4LHD therefore becomes deenergized.

If, now, the operator restores both signals ZRA and tlRA to their stop positions by manipulation of the leverscontrolling relays QRHS and 4Rl-IS, before a train in the east-bound direction enters the stretch of track within the limits of the sections represented in the drawing, the apparatusillustrated in the drawing will operate in the usual manner to pick up approach locking relay @RAS and thus release the locking between the opposing signals. That is to say, signal ARA going to stop closes its contact a in the circuit of relay LlRP, and reverses the positions of contacts b and c in the circuit of relay ERHD so that relay ZRHD is operated to its normal position. Signal ERA will be put to stop through the deenergization of relay ZRAl-I and under the conditions assumed, relay ZRAS will be picked up to close its contact a in the circuit or relay liLHD. Contact a of relay fRHS will be operated to its normal position, so that when relay LED picks Iup and closes its contact b in the circuit of relay Zrelay HRA to stop Without restoring relay ZRHS vto its normal position to place signal RRA to stop at the same time, the following operation takes place. Relay @RAR releases since its circuit is now open at contact b of relay ARES, signal RA thereupon operates to its O0 position and at its 45 position its contacts b and c are reversed to reverse the polarity or energiaation of relay 2Rl-ID. This closes contact a of relay RHD in .the circuit of relay LI-ID, and also operates con- .tact c of relay QRHD to its normal position to deenergize relay ERD and provide the short circuit path around its Winding. Relay SLI-ID now `at the end of the slow release A that distant relay `iLHD for one of the becomes `momentarily energizedduring the slow release time of relay 2RD overits circuitincluding contact a of relay ZRI-ID and contact a of :relay 2R13; and front contact b `of relay liLl-ID accordingly completes the pick-up circuit of relay ARAB.. Contact a of relay -ARAR closes `to complete the stick circuit patharound contact b of relay QLHD, andwhen the `latter relay releases period of relay ERD, the stick circuit of relay liRAR holds the relay ARAR energized. At this time, ofcourse, relay ZRAS Which has a frntcontact `normally closed in the circuit of relay GLHD, is released due lto the fact that relay ZRHS for signal ZRA Ais in its reverse position.

The reversal of `relay ZRHD results in signal 2RA going to its caution or .45 position atwhich position contact a of signal 2BA closes, while operation of signal liRA to its stop position results in contact `a of that signal closing in its 0 position. The operation of the signal contacts a `of signals 2RA and liRA to the positions in which vthey close to complete the energizing circuit for relay AFR?, takes an appreciable length of time, much longer than the time that relay ZRD holds its front contacta closed. As a result, therefore, relay GRP does not pick up to close its front `contact a during the interval that relay liLI-ID is energized over the slow releasing front contact of relay ERD so that but for the introduction of front contact o oi the stick relay `lRAR in the circuit` of relay IERAS, the momentarylenergiza- Ation of relay fiLI-ID could not be used in the con- -trol of the approach locking relay RAS. .How-

ever, relay QRAR is picked up by the momentary -f energization of relay LHD, and is held picked up over its stick circuit after relay ALI-ID reileases so that when relay 4R13 subsequently picks up, the pick-up circuit of relay LiRAS can be established and that relay accordinglypicks up. A

AWith relay IRAS picked up inthe manner described, and relay llLAS also in its picked-up position, the approach locking is released and the operator is now in a position to. select any one of the routes over switch 3. l

From the foregoing description it is apparent opposing signals 4LA, is momentarily energizedtofeffect the release of the approach locking .provided for `the other opposing signal llRA. This momentary energization of relay IILHD is effected-When signal ARA is put to stop while signal ZRA is held out of its stop position, and is effected through the operation of contacts of signal ARA to their reverse position when signal QRA reaches itsfio or caution position. At the time that the contacts b and c of signal @RA reverse to reverse the energization of the distant relay ERI-ID for the approach signal ZRA, relay ALI-ID becomes m0- mentarily energized during the interval that relay ZRD operated by relay ERK-ID holds its front contacts closed,` and this momentary energization of relay llLHD closes the pick-up circuit of a Astick relay 4RAR, which relay in turn closes its front contact to provide a stick circuit path around the front contact of relay QLHD so as to maintain relay llRAR, picked up after relay LHD releases. This pickup of relay ARAB,` stores the momentary energization of relay QLHD so that after the signal repeating relay 4BP is picked H up `at the end of the appreciable time interval required for theA contacts of signal dlAzltollclose in their 0 or stop position, and the contacts operated by signal 2BA to close in their 45 position, the pick-up circuit for approach locking relay ARAS .maybe completed over a contact of relay dRAR.

The apparatus of my invention is therefore arranged to provide means `for utilizing the momentary energization of adistant relayin the control of the approach locking relay Afor'an opposing signal ina signalingsystfem which incorporates semaphore type signals .and which is inherently incapable of using the momentary energization of Athe distant .relay directly in the control of the approach lock relay.

Apparatus also has been illustrated `in the drawing to provide approach control relay `dRAS v'vitha4 track circuit releasecontrolled by relay .'iTR, anda time release `controlled by element This apparatus is represented to show a complete operative system for thecontro'l ofre- `lay 4RAS,`but,a description of the operation of this apparatus is believed to be unnecessarysince it operates in `a manner Well known in the'` art.

Although l' have hereinshown and described only one form of railway signaling apparatus embodyingrny invention, it is understood that .with the position .ofV said signal, the combination witha `signal control contact operable to a position for clearing said one opposingvsignal and having another position, an approachlocking relay for said .one opposing signal for controlling over its front contact the clearing circuit` Vfor the `other opposing signal, means controlledv by contacts,.of said one opposing signal for operating said approachsignal from caution to clear,` a signal repeating relay controlled by saidcsignal voperated contacts` to be energized only when said one opposing signal is at stop and said approach signal is either at or between itsstop and'caution positions, a `distant control relay forsaid ctherfopposing signal `momentarily energized When said approach signal operates from its clear, toits caution position whentsaid stretch between` said approach and said one opposing signa1 ,is vacant, cf an approach relay provided Witha pick-upcircuit including a frontfcontactoi said distant vcontrol i relay and a contact operated in synchronism With 4said signalcontrol contact, a stick circuit for said .approach relay including its front contact connected around the Contact of saiddistant control relay, and a circuit for said approach locking relay including a iront Contact @f said approach relay, a front` contact of `said signal repeating Hrelay and said signal.control` contactin saidother position.

"2. Infa railway signaling system for a stretch .of: railroad track provided with tivo opposing signals and an, approach signal yfor one cf said' opl@posing signalsffsaid signals `being of the semaaDhQre typehaving stop, caution and clear plosif-tionsl-and having contacts selectively operatedaccording Ato .the `position of said signal, the combinationyzitha signalcontrol contact` operable to one position for clearing said oneopposing signal and having another position, an approach locking relay for said one opposing signal for controlling over its front contact the clearing circuit for the other opposing signal, a signal repeating relay controlled by said signal operated contacts to be energized only when said one opposing signal is at stop and said approach signal is either at or between its stop and caution positions, a distant control relay for said other opposing signal momentarily energized when said approach signal operates from its clear to its caution position when said stretch between said approach and said one opposing signal is Vacant, and means controlled by contacts oi said one opposing signal for operating said approach signal between its caution and clear positions, of means controlled by said distant control relay for storing the momentary energization of that relay during the interval required by the contacts of the semaphore signals to operate between the clear and stole` positions of said one opposing signal, and a circuit for said approach locking relay including said signal control contact in its said other position and a front contact of said signal repeating relay and controlled by said storing means to be completed after release of said distant control relay.

3. In a railway signaling system for a stretch of railroad track provided with a iirst signal governing traic in one direction in said stretch, a second signal governing traic in the opposite direction in a portion of said stretch governed in one direction 'by said iirst signal, and a third signal governing traine in said one direction approaching said rst signal, said signals being of the semaphore type having stop, caution and clear positions and characterized by requiring appreciable intervals oi time to operate from one position to another and having contacts selectively operated according to the position of the signal, the combination with av signal control contact operable to one position for clearing said iirst signal and having anther position, an approach locking relay for said first signal for controlling over its iront contact the clearing circuit for said second signal, means controlled by contacts of said rst signal in its caution position for operating said third signal from its caution to its clear position, a signal repeating relay controlled by said signal operated contacts to be energized only when sad rst signal is at stop and said third signal is either at or between its stop and caution positions, a distant control relay for said second signal momentarily energized when said third signal operates from its clear to its caution position when said stretch between said third and said iirst signal is vacant, of an approach relay provided with a pick-up circuit including a front contact of said distant control relay and a contact operated in synchronism with said signal control contact, a stick circuit for said approach relay including its front contact connected around the contact of said distant control relay, and a circuit for said approach locking relay including a front contact of said approach relay, a front contact of said signal repeating relay and said signal control contact in said other position.

4. In a railway signaling system for a stretch of railroad track provided with a first signal governing traffic in one direction in said stretch and a second signal governing traffic in said one direction approaching said iirst signal, said signals being of the semaphore type having stop, caution and clear positions and characterized by requiring appreciable intervals of time to operate from lone position to another and having contacts selectively operated according to the position of the signal, the combination with a signal control contact operable to one position for clearing said rst signal and having another position, an approach locking relay for said rst signal, means controlled by contacts of said first signal in its caution position for operating said second signal from its caution to its clear position, a signal repeating relay controlled by said signal operated contacts to be energized only when said first signal is at stop and said second i signal is either in or between its stop and caution positions, another relay momentarily energized when said second signal operates from its clear to its caution position when said stretch between said second and said first signal is Vacant, of an approach relay provided with a pick-up circuit including a iront contact of saidother relay and a contact operated in synchronism with said signal control contact, a stick circuit for said approach relay includingV its front contact connected around the contact of said other relay, and a circuit for said approach locking relay including a front contact of said approach relay, a front contact of said signal repeating relay and said signal control contact in said other position.

5. In a railway signaling system for a stretch of railroad track provided with two opposing signals and an approach signal for one of said opposing signals, said signals being of the semaphore type having stop, caution and clear positions and having contacts selectively operated in accordance with the position of the signal, the combination with manually controllable means having contacts operable between a position for clearing said one opposing signal and another position, an approach locking relay for said one opposing signal for controlling over its front contact the clearing circuit for the other opposing signal, means controlled by contacts of said one opposing signal in its caution position for operating said approach signal from its caution to its clear position, a signal repeating relay controlled by said signal operated contacts to `be energized only when said one opposing signal is at stop and said approach signal is Veither in or between its stop and caution positions, a distant controlrrelay for said other opposing signal momentarily energized when said approach signal operates from its clear to its caution position when said stretch between said approach and said oneopposing signal is vacant, of an approach relay provided with a pick-up circuit including a front contact of said distant control relay and a contact operated in synchronism with said signal control contact, a stick circuit for said approach relay including its iront contact connected around the contact of said distant control relay, and a circuit for said approach locking relay including a front contact of said approach relay, a front contact of said signal repeating relay and said signal control contact in said other position.

IRA F. CADMAN.

REFERENCES CITED UNITED STATES PATENTS Name Date Allen Q.-- Feb. 13, 1945 Number 

